Electrostatic chuck having thermally isolated zones with minimal crosstalk

ABSTRACT

A substrate support assembly includes a ceramic puck and a thermally conductive base having an upper surface that is bonded to a lower surface of the ceramic puck. The thermally conductive base includes a plurality of thermal zones and a plurality of thermal isolators that extend from the upper surface of the thermally conductive base towards a lower surface of the thermally conductive base, wherein each of the plurality of thermal isolators provides approximate thermal isolation between two of the plurality of thermal zones at the upper surface of the thermally conductive base.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/820,596 filed on May 7, 2013.

TECHNICAL FIELD

Embodiments of the present invention relate, in general, to anelectrostatic chuck having multiple thermally isolated zones withminimal crosstalk.

BACKGROUND

Electrostatic chucks are used to support substrates during processing.One function of an electrostatic chuck is to regulate a temperature ofthe supported substrate. To facilitate such temperature regulation, theelectrostatic chucks may have multiple different zones, and each zonemay be tuned to a different temperature. However, conventionalelectrostatic chucks may exhibit significant crosstalk between zones. Inan example, assume that there are two adjacent zones in an electrostaticchuck, where a first zone is heated to 15° C. and the second zone isheated to 25° C. Crosstalk between these two zones may cause arelatively large portion of the first zone to actually have atemperature that is greater than 15° C. due to a proximity to the secondzone. The level of crosstalk exhibited by conventional electrostaticchucks can be too high for some applications.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that differentreferences to “an” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references mean at leastone.

FIG. 1 depicts a sectional view of one embodiment of a processingchamber.

FIG. 2 depicts a cross sectional side view of one embodiment of anelectrostatic chuck.

FIG. 3 is a graph illustrating crosstalk between thermal zones of someexample electrostatic chucks.

FIG. 4 is a top view of an electrostatic chuck, in accordance with oneembodiment.

FIG. 5 is a bottom view of an electrostatic chuck, in accordance withone embodiment.

FIG. 6 is a cross sectional side view of an electrostatic chuck, inaccordance with one embodiment.

FIG. 7 is a cross sectional side view of an electrostatic chuck assemblystack.

FIG. 8 illustrates a process for manufacturing an electrostatic chuck,in accordance with embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Described herein are embodiments of an electrostatic chuck having athermally conductive base (also called a cooling plate) with multiplethermal zones that are approximately thermally isolated from oneanother. The different thermal zones are separated by thermal isolators(also called thermal breaks) that extend from an upper surface of thethermally conductive base towards a lower surface of the thermallyconductive base. The thermal isolators may be filled with silicone,vacuum, or other thermally insulating material. Alternatively, thethermal isolators may be vented to atmosphere. The thermal isolatorsreduce crosstalk between thermal zones of the electrostatic chuck by asmuch as 50% as compared to traditional electrostatic chucks.

FIG. 1 is a sectional view of one embodiment of a semiconductorprocessing chamber 100 having a substrate support assembly 148 disposedtherein. The processing chamber 100 includes a chamber body 102 and alid 104 that enclose an interior volume 106. The chamber body 102 may befabricated from aluminum, stainless steel or other suitable material.The chamber body 102 generally includes sidewalls 108 and a bottom 110.An outer liner 116 may be disposed adjacent the side walls 108 toprotect the chamber body 102. The outer liner 116 may be fabricatedand/or coated with a plasma or halogen-containing gas resistantmaterial. In one embodiment, the outer liner 116 is fabricated fromaluminum oxide. In another embodiment, the outer liner 116 is fabricatedfrom or coated with yttria, yttrium alloy or an oxide thereof.

An exhaust port 126 may be defined in the chamber body 102, and maycouple the interior volume 106 to a pump system 128. The pump system 128may include one or more pumps and throttle valves utilized to evacuateand regulate the pressure of the interior volume 106 of the processingchamber 100.

The lid 104 may be supported on the sidewall 108 of the chamber body102. The lid 104 may be opened to allow access to the interior volume106 of the processing chamber 100, and may provide a seal for theprocessing chamber 100 while closed. A gas panel 158 may be coupled tothe processing chamber 100 to provide process and/or cleaning gases tothe interior volume 106 through a gas distribution assembly 130 that ispart of the lid 104. Examples of processing gases may be used to processin the processing chamber including halogen-containing gas, such asC₂F₆, SF₆, SiCl₄, HBr, NF₃, CF₄, CHF₃, CH₂F₃, Cl₂ and SiF₄, amongothers, and other gases such as O₂, or N₂O. Examples of carrier gasesinclude N₂, He, Ar, and other gases inert to process gases (e.g.,non-reactive gases). The gas distribution assembly 130 may have multipleapertures 132 on the downstream surface of the gas distribution assembly130 to direct the gas flow to the surface of the substrate 144.Additionally, or alternatively, the gas distribution assembly 130 canhave a center hole where gases are fed through a ceramic gas nozzle. Thegas distribution assembly 130 may be fabricated and/or coated by aceramic material, such as silicon carbide, yttria, etc. to provideresistance to halogen-containing chemistries to prevent the gasdistribution assembly 130 from corrosion.

The substrate support assembly 148 is disposed in the interior volume106 of the processing chamber 100 below the gas distribution assembly130. The substrate support assembly 148 holds the substrate 144 duringprocessing. An inner liner 118 may be coated on the periphery of thesubstrate support assembly 148. The inner liner 118 may be ahalogen-containing gas resist material such as those discussed withreference to the outer liner 116. In one embodiment, the inner liner 118may be fabricated from the same materials of the outer liner 116.

In one embodiment, the substrate support assembly 148 includes amounting plate 162 supporting a pedestal 152, and an electrostatic chuck150. The electrostatic chuck 150 further includes a thermally conductivebase 164 bonded to a ceramic body (referred to as an electrostatic puck166 or ceramic puck) via a bond 138. The electrostatic puck 166 may befabricated by a ceramic material such as aluminum nitride (AlN) oraluminum oxide (Al₂O₃). The mounting plate 162 is coupled to the bottom110 of the chamber body 102 and includes passages for routing utilities(e.g., fluids, power lines, sensor leads, etc.) to the thermallyconductive base 164 and the electrostatic puck 166. In one embodiment,the mounting plate 162 includes a plastic plate, a facilities plate anda cathode base plate.

The thermally conductive base 164 and/or electrostatic puck 166 mayinclude one or more optional embedded heating elements 176, embeddedthermal isolators 174 and/or conduits 168, 170 to control a lateraltemperature profile of the support assembly 148. The thermal isolators174 (also referred to as thermal breaks) extend from an upper surface ofthe thermally conductive base 164 towards the lower surface of thethermally conductive base 164, as shown. The conduits 168, 170 may befluidly coupled to a fluid source 172 that circulates a temperatureregulating fluid through the conduits 168, 170.

The embedded thermal isolator 174 may be disposed between the conduits168, 170 in one embodiment. The heater 176 is regulated by a heaterpower source 178. The conduits 168, 170 and heater 176 may be utilizedto control the temperature of the thermally conductive base 164, therebyheating and/or cooling the electrostatic puck 166 and a substrate (e.g.,a wafer) being processed. The temperature of the electrostatic puck 166and the thermally conductive base 164 may be monitored using a pluralityof temperature sensors 190, 192, which may be monitored using acontroller 195.

The electrostatic puck 166 may further include multiple gas passagessuch as grooves, mesas, sealing bands (e.g., an outer sealing band (OSB)and/or an inner sealing band (ISB)) and other surface features, whichmay be formed in an upper surface of the electrostatic puck 166. The gaspassages may be fluidly coupled to a source of a thermally conductivegas, such as He via holes drilled in the puck 166. In operation, the gasmay be provided at controlled pressure into the gas passages to enhancethe heat transfer between the electrostatic puck 166 and the substrate144.

The electrostatic puck 166 includes at least one clamping electrode 180controlled by a chucking power source 182. The electrode 180 (or otherelectrode disposed in the puck 166 or base 164) may further be coupledto one or more RF power sources 184, 186 through a matching circuit 188for maintaining a plasma formed from process and/or other gases withinthe processing chamber 100. The sources 184, 186 are generally capableof producing RF signal having a frequency from about 50 kHz to about 3GHz and a power of up to about 10,000 Watts.

FIG. 2 depicts a cross sectional side view of a portion of theelectrostatic chuck 150. The portion of the electrostatic chuck 150includes a region between a center 214 of the electrostatic chuck 150and an outer perimeter 216 of the electrostatic chuck 150. The termcenter of the electrostatic check 150 is used here to refer to thecenter of the electrostatic chuck 150 in a plane that is coplanar with asurface of the electrostatic chuck 150. The electrostatic chuck 150includes the electrostatic puck 166 and the thermally conductive base164 attached to the electrostatic puck 166. The electrostatic puck 166is bonded to the thermally conductive base 164 by a bond 212. The bond212 may be a silicone bond, or may include another bonding material. Forexample, the bond 212 may include a thermal conductive paste or tapehaving at least one of an acrylic based compound and silicone basedcompound. Example bonding materials include a thermal conductive pasteor tape having at least one of an acrylic based compound and siliconebased compound with metal or ceramic fillers mixed or added thereto. Themetal filler may be at least one of Al, Mg, Ta, Ti, or combinationthereof and the ceramic filler may be at least one of aluminum oxide(Al₂O₃), aluminum nitride (AlN), titanium diboride (TiB₂) or combinationthereof.

The electrostatic puck 166 has a disc-like shape having an annularperiphery that may substantially match the shape and size of a substratepositioned thereon. An upper surface of the electrostatic puck 166 mayhave numerous surface features (not shown). The surface features mayinclude an outer sealing band (OSB), an inner sealing band (ISB),multiple mesas, and channels between the mesas. In one embodiment, theelectrostatic puck 166 includes no ridges. Alternatively, theelectrostatic puck 166 may include one or both of an ISB and an OSB. Theelectrostatic puck 166 may also include multiple holes through which athermally conductive gas such as helium may be pumped.

The thermally conductive base 164 attached below the electrostatic puck166 may have a disc-like main portion. In one embodiment, the thermallyconductive base 164 is fabricated by a metal, such as aluminum orstainless steel or other suitable materials. Alternatively, thethermally conductive base 164 may be fabricated by a composite ofceramic and metal material providing good strength and durability aswell as heat transfer properties. The composite material may have athermal expansion coefficient that is substantially matched to theoverlying puck 166 in one embodiment to reduce thermal expansionmismatch. The electrostatic puck 166 may be a ceramic material such asMN or Al₂O₃, and may have an electrode (not illustrated) embeddedtherein.

In one embodiment, the electrostatic chuck 150 is divided into fourthermal zones 218, 220, 222 and 224. A first thermal zone 218 extendsfrom the center 214 of the electrostatic chuck 150 to a first thermalisolator 234. A second thermal zone 220 extends from the first thermalisolator 234 to a second thermal isolator 235. A third thermal zone 222extends from the second thermal isolator 235 to a third thermal isolator236. A fourth thermal zone extends from the third thermal isolator 236to the perimeter 216 of the electrostatic chuck 150. In alternativeembodiments, electrostatic chucks may be divided into greater or fewerthermal zones. For example, two thermal zones, three thermal zones, fivethermal zones, or another number of thermal zones may be used.

Each of the thermal zones 218, 220, 222, 224 includes one or moreconduits 226, 228, 230, 232 (also referred to as cooling channels). Theconduits 226, 228, 230, 232 may each be connected to a separate fluiddelivery line and through the separate fluid delivery line to a separateset point chiller. A set point chiller is a refrigeration unit thatcirculates a fluid such as a coolant. The set point chillers may deliverfluid having a controlled temperature through the conduits 226, 228,230, 232, and may control the flow rate of the fluid. Accordingly, theset point chillers may control the temperature of the conduits 226, 228,230, 232 and the thermal zones 218, 220, 222, 224 containing thoseconduits.

The different thermal zones 218, 220, 222, 224 may be maintained atdifferent temperatures. For example, the first thermal zone 218, secondthermal zone 220 and fourth thermal zone 224 are shown at 25° C. Thethird thermal zone 222 is shown at 15° C. The thermal isolators 234,235, 236 provide an increased degree or amount of thermal isolationbetween the different thermal zones, and minimize crosstalk between thethermal zones. The thermal isolators 234, 235, 236 may provideapproximate thermal isolation between thermal zones. Accordingly, somecrosstalk (e.g., heat transfer) may occur between thermal zones. Thethermal isolators extend from an upper surface of the thermallyconductive base 164 (at the interface with the bond 212) approximatelyvertically into the thermally conductive base 164. The thermal isolators234, 235, 236 extend from the upper surface towards a lower surface ofthe thermally conductive base 164, and may have various depths into thethermally conductive base 164. Because the thermal isolators 234, 235,236 extend to the upper surface of the thermally conductive base 164,they minimize heat flux between the thermal zones within theelectrostatic puck 166.

In one embodiment, thermal isolator 234 is 30 mm from a center of theelectrostatic chuck 150, thermal isolator 235 is 90 mm from the centerof the electrostatic chuck 150, and thermal isolator 236 is 134 mm fromthe center of the electrostatic chuck. Alternatively, the thermalisolators 234, 235, 236 may be located at different distances from thecenter of the electrostatic chuck 150. For example, thermal isolator 234may be located 20-40 mm from the center of the electrostatic chuck 150,thermal isolator 235 may be located 80-100 mm from the center of theelectrostatic chuck 150, and thermal isolator 236 may be located 120-140mm from the center of the electrostatic chuck 150.

A first temperature gradient 240 is shown at the interface between thesecond thermal zone 220 and the third thermal zone 222 in theelectrostatic puck 166. The first temperature gradient 240 has a hightemperature of 25° C. at a first end 242 and a low temperature of 15° C.at a second end 244. Similarly, a second temperature gradient 250 isshown at the interface between the third thermal zone 222 and the fourththermal zone 224 in the electrostatic puck 166. The second temperaturegradient 250 has a low temperature of 15° C. at a first end 252 and ahigh temperature of 25° C. at a second end 254. Crosstalk betweenthermal zones (shown in the temperature gradients) is considerably lessas compared to traditional electrostatic chucks. Such crosstalk may bereduced by around 50% as compared to traditional electrostatic chucks.For example, the increased temperature at the second thermal zone 220may have a 50% lesser effect on the temperature of the third thermalzone 222 as compared to an electrostatic chuck in which thermal breaksextend from a bottom of the thermally conductive base.

The amount of crosstalk between adjacent zones may depend on a thicknessof the electrostatic puck 166, a material composition of theelectrostatic puck 166, whether thermally managed materials are usednear the upper surface of the thermally conductive base 164, and thetemperatures at which the adjacent thermal zones are maintained.Increasing the thickness of the electrostatic puck 166 may increase acrosstalk length, while decreasing the thickness may decrease thecrosstalk length. Similarly, increasing the temperature differencebetween thermal zones may increase the crosstalk length, while reducingthe temperature differences may reduce the crosstalk length.Additionally, use of a thermally managed material may reduce thecrosstalk length.

The electrostatic chuck 150 may be used to support a substrate such as awafer during a plasma etch process, a plasma clean process, or otherprocess that uses plasma. Accordingly, an outer perimeter 216 of thethermally conductive base 164 may be coated with a plasma resistantlayer 238. In some embodiments, a surface of the electrostatic puck 166is also coated with the plasma resistant layer 238. The plasma resistantlayer 238 may be a deposited or sprayed ceramic such as Y₂O₃ (yttria oryttrium oxide), Y₄Al₂O₉ (YAM), Al₂O₃ (alumina) Y₃Al₅O₁₂ (YAG), YAlO3(YAP), SiC (silicon carbide), Si₃N₄ (silicon nitride), Sialon, AlN(aluminum nitride), AlON (aluminum oxynitride), TiO₂ (titania), ZrO₂(zirconia), TiC (titanium carbide), ZrC (zirconium carbide), TiN(titanium nitride), TiCN (titanium carbon nitride) Y₂O₃ stabilized ZrO₂(YSZ), and so on. The plasma resistant layer may also be a ceramiccomposite such as Y₃Al₅O₁₂ distributed in Al₂O₃ matrix, a Y₂O₃—ZrO₂solid solution or a SiC—Si₃N₄ solid solution. The plasma resistant layermay also be a ceramic composite that includes a yttrium oxide (alsoknown as yttria and Y₂O₃) containing solid solution. For example, theplasma resistant layer may be a ceramic composite that is composed of acompound Y₄Al₂O₉ (YAM) and a solid solution Y₂-xZr_(x)O₃ (Y₂O₃—ZrO₂solid solution). Note that pure yttrium oxide as well as yttrium oxidecontaining solid solutions may be doped with one or more of ZrO₂, Al₂O₃,SiO₂, B₂O₃, Er₂O₃, Nd₂O₃, Nb₂O₅, CeO₂, Sm₂O₃, Yb₂O₃, or other oxides.Also note that pure Aluminum Nitride as well as doped Aluminum Nitridewith one or more of ZrO₂, Al₂O₃, SiO₂, B₂O₃, Er₂O₃, Nd₂O₃, Nb₂O₅, CeO₂,Sm₂O₃, Yb₂O₃, or other oxides may be used. Alternatively, the protectivelayer may be sapphire or MgAlON.

The plasma resistant layer may be produced from a ceramic powder or amixture of ceramic powders. For example, the ceramic composite may beproduced from a mixture of a Y₂O₃ powder, a ZrO₂ powder and an Al₂O₃powder. The ceramic composite may include Y₂O₃ in a range of 50-75 mol%, ZrO₂ in a range of 10-30 mol % and Al₂O₃ in a range of 10-30 mol %.In one embodiment, the ceramic composite contains approximately 77%Y₂O₃, 15% ZrO₂ and 8% Al₂O₃. In another embodiment, the ceramiccomposite contains approximately 63% Y₂O₃, 23% ZrO₂ and 14% Al₂O₃. Instill another embodiment, the ceramic composite contains approximately55% Y₂O₃, 20% ZrO₂ and 25% Al₂O₃. Relative percentages may be in molarratios. For example, the ceramic composite may contain 77 mol % Y₂O₃, 15mol % ZrO₂ and 8 mol % Al₂O₃. Other distributions of these ceramicpowders may also be used for the ceramic composite.

During processing in a plasma rich environment, arcing may be causedinside of the thermal isolators 234, 235, 236. To avoid such arcing, thethermal isolators 234, 235, 236 may be filled with a thermally resistivedielectric material such as silicone or an organic bond material.Additionally or alternatively, tops of the thermal isolators 234, 235,236 may be covered by an electrically conductive film 237. Theelectrically conductive film 237 preferably has poor thermalconductivity to minimize thermal crosstalk between thermal zones.Accordingly, the electrically conductive film may be very thin and/ormay have a grid or wire mesh pattern. The electrically conductive filmmay have a thickness of about 200 to about 800 microns in someembodiments. In one embodiment, the electrically conductive film is analuminum alloy (e.g., T6061) and has a thickness of about 500 microns(e.g., about 0.020 inches). Alternatively, the electrically conductivefilm may be other metals or other electrically conductive materials. Theelectrically conductive film 237 may prevent arcing within the thermalisolators 234. The electrically conductive film 237 may conformapproximately to the shape of the thermal isolator 234, 235, 236 that iscovers.

In one embodiment, the thermally conductive base 164 includes anencapsulated material near or at the upper surface (e.g., where thethermally conductive base interfaces with the bond 212 and/orelectrostatic puck 166). The encapsulated material may have ananisotropic thermal conductivity. The material may be a thermallymanaged material embedded in the thermally conductive base, thethermally managed material having different thermal conductiveproperties along a first direction and a second direction. Variousbonding technologies may be used to bond the thermally managed material,such as diffusion bonding, flash bonding, lamination, soldering andbrazing.

The encapsulated or embedded material may be oriented in such a way thatthe material has good thermal conductivity (e.g., around 1500 Watts/m-K)along the perimeter of the thermally conductive base and good thermalconductivity in the vertical direction (e.g., normal to a surface of thethermally conductive base), but has poor thermal conductivity (e.g.,less than about 20 Watts/m-K) in the radial direction of theelectrostatic chuck. Such an embedded material can reduce crosstalk inthe radial direction between thermal zones. In one embodiment, theembedded material is a high thermal conductivity thermally pyrolyticgraphite layer. In one embodiment, the thermally managed material iscovered with an aluminum cover. The pyrolytic graphite may includehighly oriented graphene stacks in bulk manufactured from thermaldecomposition of hydrocarbon gas in a high temperature, chemical vapordeposition reactor. Examples of a high thermal conductivity thermallypyrolytic graphite include TC1050® Composite and TPG® by Momentive™. Inone embodiment, the embedded material is encapsulated with coefficientof thermal expansion (CTE)-matched alloys or other materials.

FIG. 3 is a graph illustrating crosstalk between thermal zones of someexample electrostatic chucks. A horizontal axis measures distance from acenter of a wafer in millimeters, and a vertical axis measurestemperature in degrees Centigrade. A first line 395 and second line 310show a crosstalk length of approximately 20 mm for conventionalelectrostatic chucks, where the crosstalk length is the minimumseparation distance between two thermal zones to maintain a desiredtemperature difference (e.g., a difference between 25° C. and 15° C. inthe illustrated example). In one embodiment, the crosstalk length isdefined as the length to go from 10% to 90% of temperature transmission.A third line 315 shows a crosstalk length of approximately 8.4 mm for anelectrostatic chuck having thermal isolators as shown in FIG. 2 and anAlN electrostatic puck 166 with a thickness of 5 mm. A fourth line 320shows a crosstalk length of approximately 6 mm for an electrostaticchuck having thermal isolators as shown in FIG. 2 and an AlNelectrostatic puck 166 with a thickness of 1 mm. In some embodiments,the electrostatic puck is AlN, has a thickness of approximately 1-5 mmand has a crosstalk length of approximately 6-8.4 mm. Other thicknessesand/or ceramic materials (e.g., Al₂O₃) may be used for electrostaticpucks.

FIG. 4 is a top view of an electrostatic chuck, in accordance with oneembodiment. The electrostatic chuck includes multiple thermal isolators415, which may correspond to thermal isolators 234, 235, 236 of FIG. 2.As shown, the thermal isolators 415 may be routed around helium deliveryholes 410 and lifter pin holes 405. Additionally, or alternatively,there may be breaks in the thermal isolators 415 where they wouldotherwise intersect with the lifter pin holes 405 and/or the heliumdelivery holes 410. Additionally, the thermal isolators may bediscontinuous due to other features within the electrostatic chuck, suchas mounting holes, electrodes, and so forth. The helium holes maydeliver helium to different heat transfer zones on the electrostaticpuck. The different heat transfer zones may be thermally isolated, andmay each be filled with helium (or other backside gas) during processingto improve heat transfer between the electrostatic chuck and a chuckedsubstrate. Having multiple heat transfer zones in the electrostatic puckmay further improve an ability to fine tune temperature control of achucked substrate.

FIG. 5 is a bottom view of an electrostatic chuck, in accordance withone embodiment. FIG. 5 shows conduits 226, 228, 230, 232 in differentthermal zones on the electrostatic chuck. As shown, the conduits andthermal zones that contain them are approximately concentric within theelectrostatic chuck. The conduits are routed around features of theelectrostatic chuck such as mounting holes, lifter pin holes, heliumholes, electrodes, and so forth. Arrows show the direction of flow ofcooling fluid within the conduits 226, 228, 230, 232. Coolant may flowthrough the conduits 226, 228, 230, 232 in a bi-directional pattern toimprove temperature uniformity within the thermal zones. In oneembodiment, the conduits have fins to increase a contact surface areabetween the conduits and the thermally conductive base that the conduitsroute through. As shown, conduit 232 is actually a set of three separateconduits that in one embodiment are connected to the same temperaturecontroller (e.g., to the same set point chiller). However, in analternative embodiment, the separate conduits may each be connected todifferent set point chillers. This may enable fine tuning of temperaturewithin different regions of a single thermal zone.

FIG. 6 is a cross sectional side view of an electrostatic chuck, inaccordance with one embodiment. Thermal isolators 234, 235 and 236 areshown. In the illustrated embodiment, thermal isolators 234 and 235 arelocated above mounting holes 620. Accordingly, the depth of the thermalisolators 234 and 235 is relatively shallow. In one embodiment, thedepth of the thermal isolators 234, 235 is about ⅛ inches to about ¼inches. Alternatively, the thermal isolators may be deeper or shallower.Thermal isolator 236 is not located above any mounting holes.Accordingly, thermal isolator 236 is has a greater depth, than thermalisolators 234 and 235. In some embodiments, the thermal isolator 236 mayhave a depth that is about 60%-90% of the total thickness of the coolingbase. In one embodiment, the thermal isolator 236 has a depth that isapproximately 75% of the total thickness of the cooling base.

FIG. 7 is a cross sectional side view of an electrostatic chuck assemblystack 700. The electrostatic chuck assembly stack 700 includes anelectrostatic chuck 150 (also referred to as an electrostatic chuckassembly) bolted to an insulation plate (e.g., a rexolite plate or otherplastic plate) 705, which provides electrical isolation from theunderneath grounded hardware (e.g., from the rest of the electrostaticchuck assembly stack. The insulation plate 705 is in turn bolted to afacilities plate 710 from underneath. The main purpose of facilitiesplate is to provide structural support for insulation plate 705 andprovide multiple coolant channels at the edge of the ESC cooling plate.A cathode base plate 715 is also bolted to a chamber body 720 fromunderneath. The cathode base plate 715 provides routing for the multiplecooling channels from incoming chiller connections to the components ofESC subsystem above it. The cathode base plate 715 also providesstructural support at the bottom of a chamber to mount the ESC on thetop. The facilities plate 710 is configured to have mounting holes thatare externally accessible from above. Accordingly, the facilities plate710 can be bolted to the cathode base plate 715 from above. This maysignificantly simplify installation and removal of a stack including theelectrostatic chuck 150, plastic plate 705 and facilities plate 710 froma chamber as compared to traditional stack configurations.

FIG. 8 illustrates a process 800 for manufacturing an electrostaticchuck, in accordance with embodiments of the present invention. At block805 of process 800, a thermally conductive base having conduits thereinis formed. The conduits are formed by a milling process, with subsequentbrazing or e-beam welding to provide vacuum integrity. For example, thethermally conductive base may be two parts, and a milling process may beperformed to form the conduits in one or both of the parts. These partsmay then be bonded together to form a single thermally conductive base.The thermally conductive base may be an aluminum, aluminum allow,stainless steel or other metal base having a disc-like shape.Alternatively, the thermally conductive base may be formed from otherthermally conductive materials. At block 810, thermal isolators areformed in the thermally conductive base. The thermal isolators may beformed by machining the thermally conductive base from the upper surfaceof the thermally conductive base to form multiple voids. The voids maybe approximately concentric voids. The voids may have approximatelyuniform depths or may have varying depths. In one embodiment, the voidsare approximately vertical trenches extending from the upper surface ofthe thermally conductive base that extend towards (but not completelyto) the lower surface of the thermally conductive base. In someembodiments, the voids are filled with an organic bond material, asilicone, or another material with low thermal conductivity.Alternatively, the voids may be sealed to vacuum, or may be vented toair.

In one embodiment, at block 815 the thermal isolators are covered withthin electrically conductive films. Various techniques may be used toform or place the films over the thermal isolators. For example, thethermally conductive base may be masked so that only areas above thethermal isolators are exposed by a mask. An electrically conductivecoating may then be deposited (e.g., by chemical vapor deposition (CVD),physical vapor deposition (PVD), atomic monolayer deposition (ALD),etc.) on the thermally conductive base. The coating could be in the formof metal film, foil, or conductive metal oxide films such as Indium-TinOxide (ITO).

In one embodiment, at block 820 a thermally managed material such asthose discussed above is embedded into the thermally conductive base ator near an upper surface of the thermally conductive base. For example,a wafer or disc of the thermally managed material may be bonded to theupper surface, and may be covered by another material such as aluminum.Alternatively, a depression may be formed (e.g., machined) into theupper surface of the thermally conductive base. A disc or wafer of thethermally managed material having the shape of the formed depression maythen be inserted into the depression and bonded to the thermallyconductive base.

At block 825, the thermally conductive base is bonded to anelectrostatic puck or other ceramic puck. The thermally conductive basemay be bonded to the electrostatic puck by an organic bond material suchas silicone.

The preceding description sets forth numerous specific details such asexamples of specific systems, components, methods, and so forth, inorder to provide a good understanding of several embodiments of thepresent invention. It will be apparent to one skilled in the art,however, that at least some embodiments of the present invention may bepracticed without these specific details. In other instances, well-knowncomponents or methods are not described in detail or are presented insimple block diagram format in order to avoid unnecessarily obscuringthe present invention. Thus, the specific details set forth are merelyexemplary. Particular implementations may vary from these exemplarydetails and still be contemplated to be within the scope of the presentinvention.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.In addition, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” When the term “about” or “approximately” is usedherein, this is intended to mean that the nominal value presented isprecise within ±25%.

Although the operations of the methods herein are shown and described ina particular order, the order of the operations of each method may bealtered so that certain operations may be performed in an inverse orderor so that certain operation may be performed, at least in part,concurrently with other operations. In another embodiment, instructionsor sub-operations of distinct operations may be in an intermittentand/or alternating manner.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. The scope of the invention should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

1. A substrate support assembly comprising: a ceramic puck; and athermally conductive base having an upper surface that is bonded to alower surface of the ceramic puck, wherein the thermally conductive basecomprises: a plurality of thermal zones; and a plurality of thermalisolators that extend from the upper surface of the thermally conductivebase towards a lower surface of the thermally conductive base, whereineach of the plurality of thermal isolators provides a degree of thermalisolation between two of the plurality of thermal zones at the uppersurface of the thermally conductive base.
 2. The substrate supportassembly of claim 1, wherein at least one of the plurality of thermalisolators is discontinuous.
 3. The substrate support assembly of claim1, wherein the plurality of thermal isolators have varying depths. 4.The substrate support assembly of claim 3, wherein the thermallyconductive base has mounting holes, and wherein one or more thermalisolators of the plurality of thermal isolators that are proximate tothe mounting holes have shallower depths than other thermal isolators ofthe plurality of thermal isolators that are not proximate to themounting holes.
 5. The substrate support assembly of claim 1, furthercomprising: a plasma resistant layer coating a side of the thermallyconductive base.
 6. The substrate support assembly of claim 1, whereinthe plurality of thermal zones comprises four thermal zones and theplurality of thermal isolators comprises three thermal isolators.
 7. Thesubstrate support assemble of claim 6, wherein a first thermal isolatorof the plurality of thermal isolators is 20-40 mm from a center of thesubstrate support assembly, a second thermal isolator of the pluralityof thermal isolators is 80-100 mm from the center of the substratesupport assembly, and a third thermal isolator of the plurality ofthermal isolators is 120-140 mm from the center of the substrate supportassembly.
 8. The substrate support assembly of claim 1, wherein theplurality of thermally conductive isolators comprise a plurality ofvoids, and wherein the plurality of voids are filled with silicone, areunder vacuum, or are vented to atmosphere.
 9. The substrate supportassembly of claim 1, further comprising: a plurality of electricallyconductive films over the plurality of thermal isolators and conformingapproximately to shapes of the plurality of thermal isolators, theplurality of electrically conductive films having poor thermalconductivity.
 10. The substrate support assembly of claim 1, whereineach of the plurality of thermal zones comprises at least one conduitcoupled to a distinct set point chiller.
 11. The substrate supportassembly of claim 1, further comprising: a plastic plate mechanicallyattached to the lower surface of the thermally conductive base; afacilities plate mechanically attached to a lower surface of the plasticplate; and a cathode base plate, wherein the facilities plate is boltedto the cathode base plate via bolts that extend through the facilitiesplate into the cathode base plate.
 12. The substrate support assembly ofclaim 1, further comprising: a thermally managed material embedded inthe thermally conductive base, the thermally managed material havingdifferent thermal conductive properties along a first direction and asecond direction.
 13. The substrate support assembly of claim 12,wherein the thermally managed material comprises a high thermalconductivity thermally pyrolytic graphite layer.
 14. The substratesupport assembly of claim 12, wherein the thermally managed material hasa first thermal conductivity along a perimeter of the thermallyconductive base and normal to the upper surface, and wherein thethermally managed material has a second thermal conductivity in a radialdirection of the substrate support assembly, wherein the second thermalconductivity is lower than the first thermal conductivity.
 15. Thesubstrate support assembly of claim 1, wherein the ceramic puckcomprises MN, has a thickness of approximately 1-5 mm, and has acrosstalk length of approximately 6-8.4 mm.
 16. A thermally conductivebase for an electrostatic chuck comprising: a plurality of approximatelyconcentric thermal zones; and a plurality of thermal isolators thatextend from an upper surface of the thermally conductive base towards alower surface of the thermally conductive base, wherein each of theplurality of thermal isolators provides a degree of thermal isolationbetween two of the plurality of thermal zones at the upper surface ofthe thermally conductive base.
 17. The thermally conductive base ofclaim 16, further comprising: a material having an anisotropic thermalconductivity embedded in the thermally conductive base at the uppersurface.
 18. The thermally conductive base of claim 16, wherein theplurality of thermally conductive isolators comprise a plurality ofvoids, and wherein the plurality of voids are filled with silicone, areunder vacuum, or are vented to atmosphere.
 19. A method of manufacturingan electrostatic chuck, comprising: forming a thermally conductive basehaving a plurality of conduits; forming a plurality of thermal isolatorsin the thermally conductive base, wherein the plurality of thermalisolators extend from an upper surface of the thermally conductive basetowards a lower surface of the thermally conductive base, wherein theplurality of thermal isolators define a plurality of thermal zones inthe thermally conductive base, and wherein each of the plurality ofthermal isolators is between adjacent conduits of the plurality ofconduits; and bonding the upper surface of the thermally conductive baseto an electrostatic puck.
 20. The method of claim 19, wherein formingthe plurality of thermal isolators comprises forming a plurality ofvoids and filling the plurality of voids with an organic bond material.